1. Field of the Invention
The present invention relates to a process for producing a corrugated plate having, on one face of a metal plate, a plurality of bent-into-contact portions extending in parallel and projecting in a ridge shape at predetermined intervals. The invention also relates to a device for producing the corrugated plate.
2. Description of the Related Art
A process for producing a channel fin for dissipating heat generated by an IC package is known from Japanese Patent Application Laid-open No. 8-83871. This channel fin is a corrugated plate having, on one face of a metal plate, a plurality of bent-into-contact portions extending in parallel and projecting in a ridge shape at predetermined intervals. The production process therefor includes a first step of molding a U-shaped bent portion by lowering a punch toward a thin starting plate supported on upper faces of a fixed die and a movable die so that the punch pushes the thin starting plate in between the fixed die and the movable die, and a second step of retracting the punch upward and then molding a heat dissipating portion by moving the movable die toward the fixed die so that the U-shaped bent portion is crushed into intimate contact.
In the first step of the above-mentioned conventional production process for the channel fin, a fresh U-shaped bent portion is molded in the thin starting plate by repeating the first step while the heat dissipating portion molded in the previous second step is fitted in a movable die groove formed in the movable die so as to position the starting thin plate. Although the heat dissipating portion is restrained by the movable die groove on the movable die side, the thin starting plate is not restrained on the opposite fixed die side. Therefore, when the punch descends between the fixed die and the movable die, it is not possible to draw in the thin starting plate on the movable die side of the U-shaped bent portion, which makes it easy for thinning to occur, but it is possible to draw in the thin starting plate on the fixed die side of the U-shaped bent portion, which makes it difficult for thinning to occur. As a result, the thickness of the U-shaped bent portion becomes uneven, thereby leading to a problem that the precision of the final product is affected.
Furthermore, when the U-shaped bent portion is crushed by moving the movable die toward the fixed die in the second step, the upper face of the thin starting plate is not pressed down. Therefore, the thin starting plate lifts up at the base of the heat dissipating portion, thus leading to a problem that the flatness is degraded.